1. Field of the Invention
The present invention relates generally to a swash plate type compressor having double-headed reciprocating pistons driven by a swash plate and adapted for use in automobile air-conditioning systems. More particularly, it relates to an improved internal lubricating system of the described type of swash plate type compressor.
2. Description of the Related Art
The U.S. Pat. No. 4,534,710 to Higuchi et al discloses a typical swash plate type compressor in which refrigerant gas is compressed by reciprocation of a plurality of double-headed pistons driven, via shoe elements, by a swash plate rotating with a drive shaft within a swash plate chamber centrally arranged in a pair of axially combined front and rear cylinder blocks. The swash plate chamber is enclosed by a pair of planar walls extending vertically to the axis of the drive shaft and axially spaced one another, and a substantially cylindrical wall extending between the pair of planar walls. The refrigerant gas returning from the air-conditioning system is initially drawn, via suction ports of the cylinder blocks and suction openings formed in the cylindrical wall of the swash plate chamber into the chamber. The refrigerant gas is then passed through suction passageways communicated with the swash plate chamber until the gas reaches suction chambers formed in front and rear housings attached to the front and rear ends of the combined cylinder blocks. The refrigerant gas in the suction chambers is then sucked into the cylinder bores and is compressed by the pistons. The compressed refrigerant gas is discharged from the cylinder bores into the discharge chambers formed in the front and rear housings, and is further sent toward the outside refrigerating circuit. However, when the refrigerant gas is drawn into the swash plate chamber during rotation of the swash plate, a major part of the refrigerant gas within the swash plate chamber is forced to flow in a circular manner along the cylindrical wall of the swash plate chamber by the effect of centrifugal force thereon as well as the thrust provided by the rotating swash plate, and is drawn into the suction passageways by the reciprocation of the pistons, and as a result, sufficient refrigerant gas is not supplied to a central region of the swash plate chamber. Therefore, a lack of lubrication of the moving elements, such as shoe elements, and radial and thrust bearings rotatably supporting the drive shaft and the swash plate, occurs. Accordingly, the operation life of the moving elements is necessarily shortened, thus decreasing the operational life of the swash plate type compressor per se.